Phase Diagram and Complexity of Mode-Locked Lasers: From Order to Disorder

Leuzzi, Luca; Conti, Claudio; Folli, Viola; Angelani, L.; Ruocco, G.

doi:10.1103/physrevlett.102.083901

Cited by 62 publications

(91 citation statements)

References 37 publications

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“…The simultaneous presence of structural disorder and nonlinearity makes these devices a fertile ground to connect photonics with advanced theoretical paradigms[2] like chaos [3], non Gaussian statistics[4], complexity [5] and also the physics of Bose Einstein condensation [6]. Historically there has been a bridge in the RL interpretation.…”

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confidence: 99%

The mode-locking transition of random lasers

2011

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The discovery of the spontaneous mode-locking of lasers, i.e., the synchronous oscillation of electromagnetic modes in a cavity, has been a milestone of photonics allowing the realization of oscillators delivering ultra-short pulses. This process is so far known to occur only in standard ordered lasers with meter size length and only in the presence of a specific device (the saturable absorber). Here we demonstrate that mode-locking can spontaneously arise also in random lasers composed by micronsized laser resonances dwelling in intrinsically disordered, self-assembled clusters of nanometer-sized particles. Moreover by engineering a novel mode-selective pumping mechanism we show that it is possible to continuously drive the system from a configuration in which the various excited electromagnetic modes oscillate in the form of several, weakly interacting, resonances to a collective strongly interacting regime. By realizing the smallest mode-locking device ever fabricated, we open the way to novel generation of miniaturized and all-optically controlled light sources.Random lasers[1] (RLs) are made by disordered highly scattering materials able to amplify light when externally pumped. The simultaneous presence of structural disorder and nonlinearity makes these devices a fertile ground to connect photonics with advanced theoretical paradigms[2] like chaos [3], non Gaussian statistics[4], complexity [5] and also the physics of Bose Einstein condensation [6]. Historically there has been a bridge in the RL interpretation. In pioneering experiments a smooth, single-peaked emission was produced by pumping finely ground laser crystals [7], or titania particles dispersed in a dye-doped solution [8,9]. This phenomenon has been dubbed RL with incoherent feedback (IFRL) because it may be explained in the framework of the diffusion approximation [10] that neglects interference and treats light rays as the trajectories of random walking particles. However this theoretical framework does not explain another kind of RL exhibitting subnanometre sharp spectral peaks [11][12][13] associated with high-Q resonances[14-17] and labeled resonant feedback random laser(RFRL).Standard multimode lasers without disorder and characterized by equispaced resonances may be driven to a synchronous regime through the so called mode-locking transition [18,19], which so far has only been shown to occur spontaneously in the presence of a saturable absorber and allows to generate ultra-short light pulses [20,21]. We show that the same transition occurs in RLs and allows to lock modes of a RFRL casting its emission in the typical IFRL spectrum and demonstrating the inherently coherent nature of the random lasing phenomenon.The system we consider is an isolated micrometer sized cluster of titania nanoparticles immersed in a rhodamine dye solution (see supplementary information (SI)). In our novel setup we use the amplified spontaneous emission (ASE) from the surrounding dye to pump the cluster. The the ASE areas are defined by shaping the beam of an e...

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The mode-locking transition of random lasers

2011

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“…On the other hand, in the RL regime above the threshold the modes acquire phase coherence and nontrivial correlations (see below), similarly to the spin-glass phase at low temperatures in disordered magnets. Moreover, as also reported for spin-glass systems [84], the RL regime presents the property of RSB [73][74][75][76][77][78][79][80].…”

Section: Theoretical Frameworkmentioning

confidence: 81%

“…A great advance in the theoretical understanding of the combined effect of amplification, nonlinearity, and disorder in RL systems was put forward in a series of articles [73][74][75][76][77][78][79][80][81][82] published along the last decade. We start by reviewing the theoretical background [73][74][75][76][77][78][79][80] underlying the variety of photonic behaviors displayed by RLs, which relies its basis on the Langevin equations that drive the dynamics of the complex slow-amplitudes modes ( ),…”

Section: Theoretical Frameworkmentioning

confidence: 99%

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Lévy Statistics and Glassy Behavior of Light in Random Fiber Lasers

Araújo¹,

Gomes²,

Raposo³

2017

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Abstract:The interest in random fiber lasers (RFLs), first demonstrated one decade ago, is still growing and their basic characteristics have been studied by several authors. RFLs are open systems that present instabilities in the intensity fluctuations due to the energy exchange among their non-orthogonal quasi-modes. In this work, we present a review of the recent investigations on the output characteristics of a continuous-wave erbium-doped RFL, with emphasis on the statistical behavior of the emitted intensity fluctuations. A progression from the Gaussian to Lévy and back to the Gaussian statistical regime was observed by increasing the excitation laser power from below to above the RFL threshold. By analyzing the RFL output intensity fluctuations, the probability density function of emission intensities was determined, and its correspondence with the experimental results was identified, enabling a clear demonstration of the analogy between the RFL phenomenon and the spin-glass phase transition. A replica-symmetry-breaking phase above the RFL threshold was characterized and the glassy behavior of the emitted light was established. We also discuss perspectives for future investigations on RFL systems.

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“…When the number of modes is huge, mean-field approximations are possible [22] and allow us to predict the existence of various phases including a mode-locked one [23]. It is possible to cast a Gross-Pitaevskii equation for the RL line shape [24] in analogy with classical wave condensation [8], as in the case of standard lasers.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of phase-locking random lasers

2013

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Laser modes may coalesce into a mode-locked state that enables femtosecond pulse compression. The nature of the interaction and the interaction time play fundamental roles in the onset of this collective state, but the investigation of the transition dynamics is technically challenging because phases are not always experimentally accessible. This is even more difficult for random lasers, a kind of disordered laser in which energies in play are much smaller than in the ordered macroscopic case. Here we investigate experimentally and numerically the dynamics of the phase-locking transition in a random laser. We developed an experimental setup able to pump individual modes with different pulse durations and found that the mode-locked regime builds only for quasicontinuous pumping, resulting in an emission linewidth dependent on the pump duration. Numerical simulation confirms experimental data.

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Phase Diagram and Complexity of Mode-Locked Lasers: From Order to Disorder

Cited by 62 publications

References 37 publications

The mode-locking transition of random lasers

The mode-locking transition of random lasers

Lévy Statistics and Glassy Behavior of Light in Random Fiber Lasers

Dynamics of phase-locking random lasers

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Phase Diagram and Complexity of Mode-Locked Lasers: From Order to Disorder

Cited by 62 publications

References 37 publications

The mode-locking transition of random lasers

The mode-locking transition of random lasers

L&eacute;vy Statistics and Glassy Behavior of Light in Random Fiber Lasers

Dynamics of phase-locking random lasers

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Lévy Statistics and Glassy Behavior of Light in Random Fiber Lasers